Protected hydrazine derivative, permitting selective reaction at one N atom, followed by mild acidic cleavage of the Boc group. For preparation of, e.g. N-aminosuccinimide, free from the cyclic hydrazide, see: J. Org. Chem., 37, 2040 (1972). Similarly, reaction with carbonyl or sulfonyl halides, followed by cleavage with HCl, provides a route to monoacyl hydrazides: Synthesis, 244 (1980). It is also commonly used in the synthesis of aza-amino acids; see, for example: Synthesis, 141 (1991) and references therein. Monoalkylhydrazines can be prepared via reduction of Boc-hydrazones with borane-THF, and cleavage with HCl: J. Org. Chem., 46, 5413 (1981). Precursor of the somewhat unstable tert-butyl azidoformate, useful for introduction of the Boc protecting group, see: Org. Synth. Coll., 5, 157 (1973). Caution! Possible violent decomposition of this azide on heating.